The present invention relates to tools used In the fabrication of pipe and more particular to a simple tool used for generating geometry and layout lines required for precise cutting and joining of pipe sections in preparation for welding.
Oftentimes, due to pipe size, complexity of required joint intersect angles and final configuration of a piping system or run as it is commonly referred to, it is impractical to join the various sections of pipe by means of threaded ends requiring joints and pipe sections to be mated by annular weld beads.
To insure proper fit and joint integrity of pipe sections that intersect at various angles forming a particular joint for welding, each of the pipe sections or components are required to be cut at a specific geometry that will provide for proper fit of one to the another. The specific geometry of the cut required on either of the pipe sections is dependent upon the size and or respective size differences of each pipe component and angle of intersection required between each of the pipe components.
Due to overall size and weight of pipe sections to be joined, it is sometimes difficult if not impossible to perform layout and joining operations in a shop or location other than on sight or in the final position where the pipe sections will finally rest. Also, it is common for a configuration or run of pipe to become quite complex due to changes in direction of run or the number of intersecting joints required prior to completion.
To insure accurate welded mating of pipe sections to proper angles and predetermined specifications that comprise a particular run of pipe. It is always necessary to cut a particular geometry into the end and or circumference of pipe sections that are to be joined. The layout process including the location of the required joint, actual angle of intersection of the pipe components and the specific geometry that is to be cut on each of the pipe components is often very time consuming, especially when the work has to be performed on sight
It is commonly the case for on sight fabrication of pipe sections for a pipe fitter to work in relatively restricted confines or areas that are difficult to access requiring the pipe fitter to limit the size as well as the number of tools he can bring to the work area. As there is usually a plurality of pipe sections joined together at various angles of intersection in any given run of pipe, accuracy at each step of lay out is of extreme importance as the accuracy of the overall project will be directly effected by the precision and accuracy employed in each of the preceding steps of the layout, cutting and welding process completed on each of the individual pipe joints comprising the run It is therefore, most important that all tools required by the pipe fitter in on sight layout for preparation of pipe sections, be rugged, compact, light weight, and easy to use while still allowing the work to be completed accurately and in a timely manner.
Although there have been a number of methods employed in performing the required lay out procedures as described above, two of the oldest and most common still used for on sight lay out of cut geometry by those familiar with the art of pipe fitting are the use of templates and or, pipe fitters ordinate tables which list cut points or ordinates as outlined in various pipe fitters hand books. Templates are patterns that define cut geometry. In the past, templates have been constructed on a drafting board and are fitted around the diameter of a pipe defining an outline of the geometry required for a given cut. Templates are now however commonly offered in pre-cut form that include templates with cut geometry for all standard pipe sizes as well as most common angles. The advantages of templates is that they are readily available, compact, accurate and lend themselves to on sight use.
The above referenced pipe fitters tables which outline ordinates or points required to identify a particular geometry for layout on pipe sections, are supplied in the various pipe fitters hand books carried by most all pipe fitters as an on sight reference. Pipe fitters handbooks are compact and considered an essential tool and reference guide as they include considerable related useful data as well as the ordinate tables outlining specific points as required to generate cut geometry needed for accurate lay out of pipe sections. It is important to note that although ordinate tables or templates as outlined provide data needed for laying out a particular geometry or shape as a guide for cutting a pipe section, the actual lay out procedure however requires additional tools for establishing angular orientation, and guidelines necessary to insure proper placement of the templates or ordinate points onto the pipe sections.
There have been a number of pipe fitters lay out tools developed that deal with generating the geometry required for joining pipe sections at various angles. Although some have been relatively innovative, the tools generally fall into two categories which are, combination squaring instruments used in conjunction with templates or pipe fitters ordinate tables and, the larger and more sophisticated mechanisms designed primarily for in shop use.
The more compact combination squaring instruments in use today which lend themselves better to on sight use, comprise various types of pipe fitters squares or combination instruments and are typified by Claude D. Moran""s U.S. Pat. No. 4,380,872 xe2x80x9cPipe fitters combination instrumentxe2x80x9d issued Apr. 26th, 1983. Although Mr. Morans square is useful for squaring pipe ends or flanges. It lacks in the ability to indicate required angles other Than horizontal, vertical or 45 degrees on a pipe face easily. The tool also makes no provision for self centering across a pipe face diameter when generating angular lay out lines or transcribing lay out lines from pipe face to pipe circumference without readjustment of the tool. Although combination type lay out tools may be more versatile allowing squaring of pipe flanges or other capabilities, they are more complex to use as they require adjustments to squaring arms and or additional layout tools to complete basic lay out process as required for generating cut geometry guide lines on pipe sections.
In the category of the more sophisticated lay out tools, the xe2x80x9cEllipsoid Marker and Template Tracerxe2x80x9d U.S. Pat. No. 3835541 by Whitworth, Sep. 17th, 1974 is a typical example. This tool is one of several more complex approaches to laying out cut line geometry Systems of this type are not very compact however as they usually consist of a precision protractor equipped rotational point which attaches the tool to it""s base, and a long articulated arm equipped with a marker that can access the entire circumference of a pipe section.
Although tools of this type; when set up properly and properly attached as required to the pipe or work piece being laid out have the ability to accurately indicate cut geometry, the proper angle and the location of the necessary cuts without templates or ordinate tables, they are not light weight or rugged, requiring that they generally be used in large shop environments or areas that do not restrict movement of the tool, the articulated arm or it""s component parts
The layout tool of the present invention overcomes the limitations of the tools outlined above in that it is an accurate and simple squaring tool. It is rugged in that there are no delicate components, light weight in that it can be manipulated with one hand, compact, allowing for use in confined spaces and easily portable as it can be carried in a large pocket or small tool bag. The tool is designed to be used in conjunction with common readily available pre made templates or pipe fitters ordinate tables and accurately provides for the primary steps necessary for laying out pipe sections for joining including angular dissecting of the end of pipe or any round object on a vertical plane, transcribing of the angled lines to the pipe circumference and providing for linear measurements as required for lay out of cut geometry on pipe sections Solid one piece construction of the tool frame make it inexpensive to manufacture and extremely rugged. The lay out tool of this invention has only one moving part which is the small proactor level arrangement inlaid in the frame of the tool for orienting the straight edge to an infinite number of angles on the face of a pipe. A set of squaring pins are provided which locate on the circumference of pipe and provide for self centering of the straight edge across the diameter of a pipe face when laying out angles. The squaring pins are long enough to engage the face of a pipe section when the tool is positioned on the circumference of a pipe with the straight edge parallel to the longitudinal center line of the pipe providing for easy transcribing of the angular face lines to the circumference of pipe section. Squaring pins allow for fast and simple orientation of the tool during the layout process and provide for proper positioning of templates on pipe circumference and laying out of cut points as specified by ordinate tables required for generating the geometry needed to accurately cut and fit pipe components together at various angles of intersection.
It is an object of this invention to provide a simple rugged and compact layout tool that is used in conjunction with pre-made templates and or pipe fitters layout tables, will accommodate a wide range of pipe diameters, can be manipulated in confined spaces and is capable of self centering a straight edge across a diameter of pipe or any circular member oriented in a vertical plane. It is also an objective of the present invention to provide for a means of identifying an infinite number of angles on a circular member orientated on a vertical plane. It is also an object of this invention to provide a tool equipped with a self aligning member which provides for linear measurement as well as a guide for the scribing of lines on a pipe circumference substantially parallel to the pipe longitudinal centerline.
The layout tool in according to this invention will be more clearly defined by the detailed description of the preferred embodiment and the drawings which follow where